The Influence of Labels,Non‐Labeling Sounds,and Source of Auditory Input on 9‐ and 15‐Month‐Olds' Object Categorization

This experiment examines the joint influence of auditory and social cues on infants' basic‐level and global categorization. Nine‐ and fifteen‐month‐olds were familiarized to a series of category exemplars in an object‐examining task. Objects were introduced with a labeling phrase, a non‐labeling sound, or no sound, and auditory input was presented orally by the experimenter or played on a hidden voice recorder. Novel objects from the familiarized category and a contrasting category were then presented. Results of analyses performed on novelty preference scores indicated that infants demonstrated basic‐level categorization in all conditions. However, infants at both age levels only demonstrated global categorization when labeling phrases were introduced. In addition, labels led to global categorization in 9‐month‐olds regardless of the source of those labels; however, labels only led to global categorization in 15‐month‐olds when the labels were presented orally by the experimenter.     

A Global‐to‐Basic Trend in Early Categorization: Evidence From a Dual‐Category Habituation Task

A series of 3 experiments are reviewed in which infants between 4 and 10 months of age were familiarized with members of 2 basic‐level object categories. The degree of distinctiveness between categories was varied. Preference tests were intended to determine whether infants formed a single category representation (at a more global level) or 2 basic‐level representations. Across 3 experiments, 10‐month‐old infants appeared to have formed multiple basic‐level categories, whereas younger infants tended to form broader, more inclusive representations. The tendency to form multiple categories was influenced to some extent by category distinctiveness. Whereas 10‐month‐olds formed separate categories for all contrasts, 7‐month‐olds did so only when the 2 familiarized categories were from separate global domains. A perceptual account of the global‐to‐basic shift in early categorization is offered. Task dependencies in early categorization are also discussed.     

A Sex Difference in Mental Rotation in Infants: Convergent Evidence

Quinn and Liben (2008) reported a sex difference on a mental rotation task in which 3‐ to 4‐month‐olds were familiarized with a shape in different rotations and then tested with a novel rotation of the familiar shape and its mirror image. As a group, males but not females showed a significant preference for the mirror image, a pattern paralleled at the individual level (with most males but less than half the females showing the preference). Experiment 1 examined a possible explanation for this performance difference, namely, that females were more sensitive to the angular differences in the familiarized shape. Three‐ to 4‐month‐olds were given a discrimination task involving familiarization with a shape at a given rotation and preference testing with the shape in the familiarized versus a novel rotation. Females and males preferred the novel rotation, with no sex difference observed. This finding did not provide support for the suggestion that the sex difference in mental rotation is explained by differential sensitivity to angular rotation. Experiment 2 revealed that the sex difference in mental rotation is observed in 6‐ to 7‐month‐olds and 9‐ to 10‐month‐olds, suggesting that a sex difference in mental rotation is present at multiple ages during infancy.     

The Effect of Vocabulary Size on Toddlers' Receptiveness to Unexpected Testimony About Category Membership

Children must be willing to accept some of what they hear “on faith,” even when that testimony conflicts with their own expectations. The study reported here investigated the relation among vocabulary size, object recognition, and 24‐month‐olds' (N = 40) willingness to accept potentially surprising testimony about the category to which an object belongs. Results showed that children with larger vocabularies were better able to recognize atypical exemplars of familiar categories than children with smaller vocabularies. However, they were also most likely to accept unexpected testimony that an object that looked like a member of one familiar category was actually a member of another. These results indicate that 24‐month‐olds trust classifications provided by adult labeling patterns even when they conflict with the classifications children generate on their own.     

Relating 7‐Month‐Olds Visuo‐Spatial Working Memory to Other Basic Mental Skills Assessed With Two Different Versions of the Habituation–Dishabituation Paradigm

This study examines the relationship between various basic mental processing abilities in infancy. Two groups of 7‐month‐olds received the same delayed‐response task to assess visuo‐spatial working memory, but two different habituation–dishabituation tasks to assess processing speed and recognition memory. The single‐stimulus group (N = 32) was familiarized with only one abstract stimulus, whereas the categorization group (N = 32) received varying exemplars of the same kind. In the categorization group, infants high on working memory showed stronger habituation and dishabituation responses than infants scoring low in working memory. No corresponding relations were found for the single‐stimulus group. This suggests that working memory performance is systematically linked to other basic mental skills in 7‐month‐olds, but that corresponding relations may not get evident in any kind of habituation–dishabituation procedure. Implications for understanding the complex interplay of basic mental abilities in infancy will be discussed.     

Integrated Emotion Processing in Infancy: Matching of Faces and Bodies

Accurate assessment of emotion requires the coordination of information from different sources such as faces, bodies, and voices. Adults readily integrate facial and bodily emotions. However, not much is known about the developmental origin of this capacity. Using a familiarization paired‐comparison procedure, 6.5‐month‐olds in the current experiments were familiarized to happy, angry, or sad emotions in faces or bodies and tested with the opposite image type portraying the familiar emotion paired with a novel emotion. Infants looked longer at the familiar emotion across faces and bodies (except when familiarized to angry images and tested on the happy/angry contrast). This matching occurred not only for emotions from different affective categories (happy, angry) but also within the negative affective category (angry, sad). Thus, 6.5‐month‐olds, like adults, integrate emotions from bodies and faces in a fairly sophisticated manner, suggesting rapid development of emotion processing early in life.     

The Development of Selective Attention Orienting is an Agent of Change in Learning and Memory Efficacy

This study examined whether the developmental transition from facilitation‐based orienting mechanisms available very early in life to selective attention orienting (e.g., inhibition of return, IOR) promotes better learning and memory in infancy. We tested a single age group (4‐month‐olds) undergoing rapid development of attention orienting mechanisms. Infants completed a spatial cueing task designed to elicit IOR, in which cat or dog category exemplars consistently appeared in either the cued or noncued locations. Infants were subsequently tested on a visual paired comparison of exemplars from these cued and noncued animal categories. As expected, infants showed either facilitation‐based orienting or the more mature IOR‐based orienting during spatial cueing/encoding. Infants who demonstrated IOR‐based orienting showed memory for both specific exemplars and broader category learning, whereas those who showed facilitation‐based orienting showed weaker evidence of learning. Attention orienting also interacted with previous pet experience, such that the number of pets at home influenced learning only when infants engaged facilitation‐based orienting during encoding. Learning in the context of IOR‐based orienting was stable regardless of pet experience, suggesting that selective attention serves as an online learning mechanism during visual exploration that is less sensitive to prior experience.     

Object Function and Categorization in Infancy: Two Mechanisms of Facilitation

Does function facilitate categorization by focusing infants' attention generally on all commonalities among objects or specifically on functionally relevant properties? After familiarization to a novel category, 18‐month‐olds selected another category member from a pair of previously unseen test objects. In Experiments 1 and 2, infants chose globally similar over functionally similar and novel test objects. Functionally similar and novel test objects were chosen equally. These data suggest that function facilitates categorization through a general attention‐enhancing mechanism. However, when functions were more uniquely and transparently tied to object properties in Experiments 3 and 4, infants chose functionally similar over novel test objects. Globally and functionally similar test objects were chosen equally. Therefore, a specific attention‐enhancing mechanism also sometimes supports categorization.     

Second‐Order Correlation Learning of Dynamic Stimuli: Evidence from Infants and Computational Modeling

We present two habituation experiments that examined 20‐ and 26‐month‐olds’ ability to engage in second‐order correlation learning for static and dynamic features, whereby learned associations between two pairs of features (e.g., P and Q, P and R) are generalized to the features that were not presented together (e.g., Q and R). We also present results from an associative learning mechanism that was implemented as an autoencoder parallel distributed processing (PDP) network in which second‐order correlation learning is shown to be an emergent property of the dynamics of the network. The experiments and simulation demonstrate that 20‐ and 26‐month‐olds as well as neural networks are capable of second‐order correlation learning in a category context for internal features of dynamic objects. However, the model predicts—and Experiment 3 demonstrates—that 20‐ and 26‐month‐olds are unable to encode second‐order correlations in a noncategory context for dynamic objects with internal features. It is proposed that the ability to learn second‐order correlations represents a powerful but as yet unexplored process for generalization in the first years of life.     

Young Infants' Performance in the Object‐Variation Version of the Above‐Below Categorization Task: A Result of Perceptual Distraction or Conceptual Limitation?

Five experiments were conducted to examine the performance of young infants on above versus below categorization tasks. Experiments 1 and 2 showed that infants did not form abstract categorical representations for above and below when familiarized with different objects depicted in a constant spatial relation relative to a horizontal bar and tested on a novel object depicted in the familiar and novel spatial relation. Experiments 3 through 5 examined perceptual‐attentional distraction versus conceptually based generalization explanations for young infant performance in the object‐variation version of the above‐below categorization task. Experiments 3 and 4 demonstrated that infants still did not form abstract categorical representations for above and below when object variation was removed from the familiarization trials or when object novelty was reduced during the preference test trials. However, Experiment 5 showed that 3‐ and 4‐month‐olds succeeded on the above versus below categorization task when familiarized with object variation and preference tested with a familiar versus novel object‐bar relation. These results indicate that young infants can form categorical representations for above and below in the object‐variation version of the above‐below categorization task, but that such representations are specific to the particular objects presented. Young infant performance in the object‐variation version of the above‐below categorization task thus reflects a conceptually based generalization limit rather than a problem of perceptual‐attentional distraction.     

Mechanisms of Visual Object Recognition in Infancy: Five‐Month‐Olds Generalize Beyond the Interpolation of Familiar Views

This work examined predictions of the interpolation of familiar views (IFV) account of object recognition performance in 5‐month‐olds. Infants were familiarized to an object either from a single viewpoint or from multiple viewpoints varying in rotation around a single axis. Object recognition was then tested in both conditions with the same object rotated around a novel axis. Infants in the multiple‐views condition recognized the object, whereas infants in the single‐view condition provided no evidence for recognition. Under the same 2 familiarization conditions, infants in a 2nd experiment treated as novel an object that differed in only 1 component from the familiar object. Infants' object recognition is enhanced by experience with multiple views, even when that experience is around an orthogonal axis of rotation, and infants are sensitive to even subtle shape differences between components of similar objects. In general, infants' performance does not accord with the predictions of the IFV model of object recognition. These findings motivate the extension of future research and theory beyond the limits of strictly interpolative mechanisms.     

ACKNOWLEDGMENT OF GUEST REVIEWERS

This study explored 14‐month‐old infants' ability to form novel word‐spatial relation associations. During habituation, infants heard 1 novel word (e.g., teek) while viewing dynamic containment events (i.e., Big Bird placed in a box) and, on other habituation trials, a second novel word (e.g., blick) while viewing dynamic support events (i.e., Big Bird placed on the box). Each novel word was presented in a sentence (e.g., “She's putting Big Bird teek the box”). During the test, infants discriminated an event that maintained the habituation word‐relation pairing from one that presented a switch in this pairing. The results indicate that 14‐month‐olds can learn to form word‐relation associations quickly, requiring only a few minutes of experience with each word‐relation pairing.     

A Comparison of Infants' Categorization in Paired and Successive Presentation Familiarization Tasks

Three experiments directly compared infants' categorization in variations of the visual familiarization task. In each experiment, 4‐ or 6‐month‐old infants were familiarized with a collection of dogs or cats and then their response to novel dogs and cats was assessed. In Experiment 1, 4‐month‐old infants responded to the exclusive distinction of dogs or cats when tested in a paired‐comparison task. In Experiments 2 and 3, 6‐month‐old infants, but not 4‐month‐old infants, responded to this same distinction in a successive presentation task, even when the amount of familiarization was equated to that of the paired comparison task. Therefore, familiarization with a particular set of stimuli does not induce infants to respond to a single category but rather they respond to different categories depending on features of the task.     

Six‐Month‐Olds' Detection of Clauses Embedded in Continuous Speech: Effects of Prosodic Well‐Formedness

Three experiments investigated the role of prosodic structure for infants' recognition of embedded word sequences. Six‐month‐olds were familiarized with 2 versions of the same sequence, 1 corresponding to a well‐formed prosodic unit and the other to a prosodically ill‐formed sequence (although a successive word series). Next, infants heard 2 test passages. One included the well‐formed unit, and the other included the ill‐formed sequence. In Experiment 1, infants listened longer to the passage containing the well‐formed unit, suggesting that such units, even when they are embedded, are better recognized. Experiments 2 and 3 showed that this better recognition does not depend on an acoustic match between the familiarized sequences and their later embeddings. This suggests that the advantage of the well‐formed unit is at least partially due to infants' use of prosody to parse continuous speech.     

5‐Month‐Olds’ Categorization of Novel Objects: Task and Measure Dependence

To examine key parameters of the initial conditions in early category learning, two studies compared 5‐month‐olds’ object categorization between tasks involving previously unseen novel objects, and between measures within tasks. Infants in Experiment 1 participated in a visual familiarization–novelty preference (VFNP) task with two‐dimensional (2D) stimulus images. Infants provided no evidence of categorization by either their looking or their examining even though infants in previous research systematically categorized the same objects by examining when they could handle them directly. Infants in Experiment 2 participated in a VFNP task with 3D stimulus objects that allowed visual examination of objects’ 3D instantiation while denying manual contact with the objects. Under these conditions, infants demonstrated categorization by examining but not by looking. Focused examination appears to be a key component of young infants’ ability to form category representations of novel objects, and 3D instantiation appears to better engage such examining.     

A Comparison of Visual Familiarization and Object‐Examining Measures of Categorization in 9‐Month‐Old Infants

Three studies were conducted to determine whether differential patterns of categorization observed in studies using visual familiarization and object‐examining measures hold up as procedural confounds are eliminated. In Experiment 1, we attempted as direct a comparison as possible between visual and object‐examining measures of categorization. Consistent with previous reports, 9‐month‐old infants distinguished a basic‐level contrast (dog–horse) in the visual task, but not in the examining task. Experiment 2 was designed to reduce levels of nonexploratory activity in an examining task; 9‐month‐olds again failed to distinguish categories of dogs and horses. In Experiment 3, we adopted a paired‐comparison test format in the object‐examining task. Infants did display a novel category preference under paired testing conditions. The results suggest that the different patterns of categorization often seen in looking and touching tasks are a reflection, not of different categorization processes, but of the differential sensitivity of the tasks.     

Retrieval Protracts Deferred Imitation by 6‐Month‐Olds

Past research using a deferred imitation task has shown that 6‐month‐olds remember a 3‐part action sequence for only 1 day. The concept of a time window suggests that there is a limited period within which additional information can be integrated with a prior memory. Its width tracks the forgetting function of the memory. This study asked if retrieving the memory of the modeled actions at the end of the time window protracts its retention, if the type of retrieval (active or passive) differentially influences retention, and if the retrieval delay influences its specificity. In Experiment 1, 6‐month‐olds either imitated the modeled actions (active retrieval group) or merely watched them modeled again (passive retrieval group) 1 day after the original demonstration. Both groups showed deferred imitation after 10 days. In Experiment 2, 6‐month‐olds who repeatedly retrieved the memory at or near the end of the time window deferred imitation for 2.5 months. In Experiment 3,6‐month‐olds spontaneously generalized imitation late in the time window after 1 prior retrieval, whether it was active or passive. These studies reveal that the retention benefit of multiple retrievals late in the time window is huge. Because most retrievals are undoubtedly latent, the contribution of repeated events to the growth of the knowledge base early in infancy has been greatly underestimated.     

Functional Elements in Infants' Speech Processing: The Role of Determiners in the Syntactic Categorization of Lexical Elements

How do children determine the syntactic category of novel words? In this article we present the results of 2 experiments that investigated whether German children between 12 and 16 months of age can use distributional knowledge that determiners precede nouns and subject pronouns precede verbs to syntactically categorize adjacent novel words. Evidence from the head‐turn preference paradigm shows that, although 12‐ to 13‐month‐olds cannot do this, 14‐ to 16‐month‐olds are able to use a determiner to categorize a following novel word as a noun. In contrast, no categorization effect was found for a novel word following a subject pronoun. To understand this difference we analyzed adult child‐directed speech. This analysis showed that there are in fact stronger co‐occurrence relations between determiners and nouns than between subject pronouns and verbs. Thus, in German determiners may be more reliable cues to the syntactic category of an adjacent novel word than are subject pronouns. We propose that the capacity to syntactically categorize novel words, demonstrated here for the first time in children this young, mediates between the recognition of the specific morphosyntactic frame in which a novel word appears and the word‐to‐world mapping that is needed to build up a semantic representation for the novel word.     

Memory for One‐Time Experiences in the Second Year of Life: Implications for the Status of Episodic Memory

Memory based on a one‐time experience is an important element of its definition as “episodic.” Infants' memories for one‐time experiences over long delays are largely unexplored. Using elicited imitation, we tested 20‐ and 16‐month‐olds' (Experiment 1) and 13‐month‐olds' (Experiment 2) memories as a function of number of experiences and delay. Over 1 month, 20‐ and 16‐month‐olds remembered individual actions of one‐time events; 20‐month‐olds also remembered temporal order; with verbal reminders, 16‐month‐olds did as well. Over 3 months, recall depended on multiple experiences. Thirteen‐month‐olds' required multiple experiences, even over 1 month. The findings speak to the gradual emergence of an important element of episodic memory, namely the ability to preserve memories of one‐time experiences over long periods of time.     

Newborns' Perceptual Categorization for Closed and Open Geometric Forms

This study explored newborns' ability to perceive perceptual similarities between different exemplars of 2 broad classes of simple shapes: closed and open geometric forms. Three experiments were carried out using a visual paired‐comparison task. Evidence showed that, after familiarization either to closed‐shaped or to open‐shaped forms, newborns manifested a novelty preference for a novel‐category rather than for a familiar‐category exemplar (Experiment 1). This result could not be explained either as a consequence of the newborns' inability to discriminate between instances of the same category of simple geometric forms (Experiment 2), or as a consequence of a spontaneous preference for the novel‐category exemplars (Experiment 3). Overall, findings revealed that newborns are able to form broad categories of distinguishable geometric shapes by relying on the shapes' perceptual similarity.